1. Field of the Invention
This invention generally relates to a thermal recording apparatus, and, in particular, to a thermal recording apparatus using a detachable ink sheet cassette containing a roll of ink sheet for use in transfer type thermal recording.
2. Description of the Prior Art
Recently, a thermal recording apparatus has been widely used because of its simple nature in mechanism and structure. In particular, a thermal recording apparatus of the type in which an ink sheet is fed together with recording paper to transfer part of the ink of the ink sheet to the recording paper to carry out transfer type recording is often used in various machines, such as facsimile machines.
However, in such a prior art thermal recording apparatus, since an ink sheet was directly mounted on a housing of the apparatus through a spool or the like and the ink sheet was extremely thin, the ink sheet tended to be slackened and creases tended to be formed. In addition, replacement of ink sheets was difficult to carry out.
Under the circumstances, it has been previously proposed to provide a separate ink sheet cassette containing therein an ink sheet extending between a supply spool and a take-up spool, which may be detachably mounted in a thermal recording apparatus of a facsimile machine as disclosed in a Japanese Patent Laid-open Publication No. 63-296971, which has been assigned to the assignee of this application. FIG. 10 illustrates an ink sheet cassette 1 of the invention disclosed in the above-mentioned patent application, and, as shown, it includes a cassette case 2 housing therein an ink sheet 3 which is wound around a supply spool 3a (paper tube) and which has its leading end fixedly attached to a take-up spool 4. A pair of support members 5 and 6 is fitted into the opposite ends of the supply spool 3a. These support members 5 and 6 are rotatably supported on the cassette case 2 and thus the roll of ink sheet 3 is rotatably supported in the cassette case 2 through the support members 5 and 6 and the supply spool 3a. The support member 6 is formed with a knob 6a and a gear 6b, so that the ink sheet 3 may be rewound manually by grabbing the knob 6a and rewinding can also be effected through the gear 6b.
A pair of support members 7 and 8 is fitted into the opposite ends of the take-up spool 4, and the support member 8 is formed with a knob 8a and a take-up gear 8b. The take-up gear 8b serves to transmit a rotating force from the main body of the thermal recording apparatus to the take-up spool 4 to thereby have the ink sheet 3 wound around the take-up spool 4.
The cassette case 2 is formed with a pair of pin receiving portions 9 and 10 one on each of the opposite sides of the cassette case 2, and these pin receiving portions 9 and 10 receive therein respective pins provided in the main body of the thermal recording apparatus, as will be made clear later. The ink sheet cassette 1 is detachably set in position inside the thermal recording apparatus through engagement between these pins and the pin receiving portions 9 and 10 of the ink sheet cassette 1.
Thus, at the time of replacement of ink sheets, the entire ink sheet cassettes 1 are replaced, so that replacement of ink sheets can be carried out extremely easily without any skills and experiences, and there is no chance of forming creases and slackness in the ink sheet 3 when set in position.
However, in such a prior art thermal recording apparatus, as described above, since the ink sheet cassette 1 is detachably set in position through engagement between the two pins of the thermal recording apparatus and the two pin receiving portions 9 and 10 of the cassette case 2, the positional accuracy in setting the ink sheet cassette 1 in the associated thermal recording apparatus is not necessarily sufficient and a sufficient accuracy is not necessarily obtained in mesh between gears of the thermal recording apparatus and the associated gears of the ink sheet cassette 1.